Nasdaq Inc. is wading into a debate over high-speed trading in the U.S. Treasury market with a system it says can shield investors from predatory behavior.

The $12.7 trillion Treasury market has come under regulatory scrutiny following a “flash crash” in October 2014, when the yield on a key bond swung wildly. Since then, some regulators and other observers have said high-speed traders are at least partly responsible for a broader...